Alun Jenkinson v Hertfordshire County Council

In a medical-treatment novus actus case, there is no special rule requiring proof that treatment was so grossly negligent as to be a completely inappropriate response before the chain of causation can be broken. The question is whether, considering all the circumstances, the defendant should fairly and justly remain responsible for the later loss. The quality and extent of the medical negligence remain relevant. On an amendment application, permission should generally be granted where the proposed defence has a real prospect of success. Existing directions and a trial date should not unfairly prevent consideration of a properly arguable defence, particularly where the defendant acted promptly and the procedural arrangements were made before the issue arose.

The claimant suffered a serious ankle fracture caused by the defendant’s admitted negligence. Subsequent surgery at an NHS hospital was alleged to have been negligent and to have caused much of the claimant’s continuing injury and loss.

The defendant applied to amend its Defence to plead that the NHS Trust was responsible for the later loss and, alternatively, that the negligent treatment was a novus actus interveniens. District Judge Vernon refused permission, holding that the proposed defence had no real prospect of success because the alleged treatment did not meet the specific threshold derived from Webb v Barclays Bank and Portsmouth Hospitals NHS Trust. The defendant appealed.

1. Appeal allowed. The refusal of permission to amend stood or fell on whether the proposed causation defence had a real prospect of success. The District Judge had not exercised a discretion, because he had refused permission on the basis that the defence could not succeed.
2. There is no rule of law that medical treatment can break the chain of causation only when it is so grossly negligent as to be a completely inappropriate response to the original injury. The assessment must address whether, in all the circumstances, the defendant should fairly, reasonably or justly remain liable for the consequences of the later treatment.
3. The degree to which treatment diverged from competent medical treatment remains relevant. At trial, the alleged failure to remove a fracture fragment, the choice of hardware and the failure of the fixation might realistically support a finding that the treatment was so badly performed that it did not amount in substance to the appropriate procedure contemplated.
4. The Court of Appeal’s discussion in Webb had not applied the proposed specific rule as a rule necessary to its decision. The court’s broader reasoning in Rahman v Arearose Ltd, that later negligence does not invariably extinguish the causative potency of an earlier tort, was consistent with the correct approach.
5. The defendant had acted promptly after obtaining the expert report. The proposed amendment arose early in the proceedings and was needed to ensure that the real issues were contested. The need for new directions, additional case management or a later trial was not, in these circumstances, a proper reason to refuse permission. The matter was remitted for consequential case-management directions, with the appeal costs dealt with as agreed.

• High Court (King’s Bench Division) — Appeal from District Judge Vernon’s order dated 20 October 2022. The appeal was allowed.